Fits 302 and 351 pedestal style cylinder heads like Ford Racing M-6049-X306 and M-6049-X307 Use with bolt-on roller rocker arms M-6564-A50, and M-6564-B351 to obtain correct lifter pre-load. Shim kit is used to reduce lifter pre-load and includes 16 each of the following thickness shims: .010" .020" .030" .040"